This invention relates to methods and apparatus for producing a discretely striped, multi-property foam and the products and articles produced thereby.
Polyol foams and their methods of manufacture are well known. These foams have many applications including: cushioning for furniture; padding for underlying carpets; seals and gaskets for a variety of uses; acoustical applications; textile laminates; energy absorbing materials; clothing; sponges; and numerous other products. Conventionally, these foams are made with homogeneous properties, and are typically monotone in color and uniform in their physical properties.
Generally, production of such foams is done with a xe2x80x9cone shotxe2x80x9d system where components, such as polyether or polyester polyols, surfactants and amine catalysts, flame retardants, blowing agents and other specialty additives are held separately and metered individually into a mixing chamber. The mixture of these components is xe2x80x9cnon-reactantxe2x80x9d, i.e. it has not begun the foaming process. Typically to initiate a chemical reaction an isocyanate is added which starts the foaming reaction process. The combination of these components in a mixture creates a pre-foam stream, i.e. a stream that has begun the reacting process but has not yet foamed. To combine the xe2x80x9cnon-reactantxe2x80x9d components and isocyanate streams thoroughly, the xe2x80x9cnon-reactantxe2x80x9d components and the isocyanate stream are passed through a mixing head. Typically the xe2x80x9cnon-reactantxe2x80x9d components enter first with the additive streams and isocyanate entering immediately thereafter. The components are thoroughly intermixed and deposited on a surface or passed through a trough device to rise and cure. Further processing may then be performed on the cured foam to achieve a desired final product. However, the result of the typical foaming process is a foam product with a uniform, homogeneous set of properties.
Several attempts have been made to increase color variety in foam products but such processes have significant drawbacks rendering production of such foams prohibitively expensive and undesirable for various applications.
A marbleization process, although increasing the variety of colors in the resultant foams, does not provide foams with a separation of one color from those of another in a repeatable, discrete pattern. This process introduces a colorant into the foam mix in an intermittent fashion such that the foam coloration is intermixed and marbleized, as seen in FIGS. 1 and 2 of Japanese patent JP62263028. This process cannot achieve discretely striped foam with a variation in color. A more regular, controlled pattern is often desired in products, for instance in the area of clothing, blankets, and novelty items to achieve a particular visual effect. The intermixing of colors in the marbleization process is so significant that no controlled visual effect is achievable. The marbleization process is only capable of providing an end product that is a wild jumble of colors.
A process to merge continuous disparate reactant foaming streams of different colors in a single foam product with heterogenous regions of color is described in U.S. Pat. No. 3,904,557. The multiple reactant streams flow in parallel and are in a liquid form when poured. Preferably they are poured through a xe2x80x9cheterogenous blenderxe2x80x9d, separating each stream with a divider plate, while mixing the compositions between the plates to promote the foaming process. Some intermixing inherently occurs when the streams hit the surface upon which they are being laid out or, alternatively, may be intentionally provided as suggested by the reference. This is likely to create a variegated pattern within the foam mass, similar to marbleization. The ""557 process then attempts to lay up the two streams of foam while they cure or just after they are poured next to one another. The resulting product inherently has a seam which would be susceptible to separation, thus making the use of these products impractical at best in any application requiring durability, such as cleaning products, blankets and clothing. The ""557 process also suffers from the increased costs in labor, machines and space for mixing, pouring, transporting and curing the multiple foam streams prior to laying them up to bond.
Despite numerous past efforts, no process has been able to achieve a cost effective, discretely striped, multi-property, segmented foam. There exists a need for a method and apparatus to produce a product having discretely striped, multi-property segments that are varied to provide distinct differentiation of properties between the segments. Such an apparatus and method would allow for increased flexibility in the variety of applications in which such a foam could be used and greater variety, particularly in the coloration of foams in general. The new system must be cost effective, preferably needing only a single foam stream. The new system should provide a durable, repeatable, discretely striped foam for commercial applications. For instance, specific commercial applications that would benefit include but are not limited to the production of blankets, clothing articles, novelty items, and similar applications.
An object of the invention is to provide a method and apparatus for producing a foam product with repeatable, discretely striped multi-property segments.
A further object of the invention is to provide a cost-effective process to produce seamless repeatable, striped, multi-property, segmented foams requiring no adhesives or bonding.
Another object of the invention is to provide a process of producing multi-property foam in a single stream.
A still further object of the invention is to provide a mixing head for manufacturing repeatable, striped, multi-property, segmented foam.
An additional object of the invention is a distinct and predictable, striped, multi-property segmented foam product.
The invention provides a process, and a foam product produced by the process, comprising the steps of providing a pre-foam stream at a first pressure, intermittently injecting an additive into the pre-foam stream at a pressure higher than the first pressure, providing a laminar flow pre-foam stream with alternating segments, pouring said laminar flow pre-foam stream onto a surface, and curing said pre-foam stream into a foam product having discrete alternating stripes or segments with different properties.
The stripes or segments of the foam can vary in chemical composition. Preferably, the additive is a coloring agent and the alternating stripes or segments vary in color. The additive may vary given ratios of at least one of a polyol, an isocyanate, and water. The product may have two or more different types of alternating stripes. The product may be a clothing article or a blanket or an insulator.
The method may further comprise the step of conveying the poured pre-foam stream in a direction generally perpendicular to the direction of pouring of the pre-foam stream. The pre-foam stream can be poured at an angle to minimize the intermixing of the pre-foam stream. The segments of the alternatingly segmented pre-foam stream are preferably generally perpendicular to the flow of the pre-foam stream. The segmented pre-foam stream can also be poured to produce an alternatingly striped foam bun rotatable about an axis of rotation. The method can further comprise pouring the pre-foam stream into a cylindrical or a rectangular form. The method can further comprise the step of pouring the pre-foam stream into a trough.
The method may also comprise peeling a striped layer or sheet of foam from the circumference of the foam bun to provide stripes generally at an angle to the axis of the cylindrical bun. The method can also include cutting a rectangular or other discretely striped foam shape from the bun.
The pre-foam stream can be provided by mixing a non-reactant stream with an isocyanate to produce a pre-foam stream. The method can include injecting the at least one additive into a laminar flow region of the pre-foam stream, providing a laminar flow segmented pre-foam stream, and/or simultaneously injecting at least one additive from at least two points of injection or, at different times, injecting at least one additive from at least two points of injection.
The method may include varying the time interval between intermittently injecting the at least one additive, or pulsing the injector orifice open and shut or varying the size of opening of the injector orifice.
The additive may be a unique marker compound or combination of compounds that can be associated with the foam product as a unique identifier. Or the additive can vary at least one of density, hardness, thickness, air permeability, tensile strength, and load bearing capacity properties of said foam. The pre-foam stream typically comprises a polyol, an isocyanate and water at given ratios. The at least one additive may vary the ratios of at least one of the polyol, isocyanate or water. The additive can comprise water or the additive may vary the polyol component of the pre-foam stream as well.
The invention further includes an article of manufacture comprising a seamless foam product having a plurality of stripes, each stripe having at least one property different from adjacent stripes. The at least one different property can comprise color, density, hardness, width, air permeability, tensile strength, and load bearing capacity. The article can be a cushioning product, a clothing product, or a bedding product. The article may have discrete stripes running predominantly perpendicular or at an angle to an axis of rotation, or to the surface of the article.
Additionally, the invention includes a method for making a foam product comprising a step for producing a pre-foam stream with a step for achieving discrete segments across the entire pre-foam stream and a step for forming a cured, discretely striped foam. The cured discretely striped foam is preferably a cylindrical bun or a rectangular mass.
The invention also provides for a method of making a striped foam, comprising, in order, the steps of preparing a pre-foam stream, intermittently injecting into the pre-foam stream an additive to form a pre-foam stream having alternating segments and pouring the pre-foam stream onto a surface, the stream curing into a multi-segmented foam having a controlled variation in properties.
An advantageous apparatus of the invention comprises a device, preferably a foam mixing head, having a mixing chamber with at least one inlet introducing components of a pre-foam stream and mixing and passing said at least one pre-foam stream at a first pressure through the chamber. The apparatus preferably includes at least one injector introducing an additive into said mixing chamber at discrete time intervals and at a pressure higher than said first pressure and an outlet, discharging a laminar flow of an alternatingly segmented pre-foam.
The foam mixing head preferably has a single pre-foam stream in the mixing head. The single pre-foam stream preferably includes an isocyanate. The injector can introduce the additive at a pressure of about 10 to about 1000 psi, preferably about 200 psi. The injector preferably ports into a laminar flow region of the mixing head and can be located generally adjacent to the outlet of the mixing chamber. The mixing head can include a programmable control unit coupled to the at least one injector and providing a predetermined pattern of alternating injection and non-injection.
The pattern of the controller can vary the duration of injection and the duration of non-injection. The injector preferably has a cycle time from open to close of about 0.1 seconds to about 10 seconds. The injector may also have a variable sized orifice for injecting additive. The mixing head may be included in a machine preferably comprising the mixing head and a conveyor located beneath the outlet of the mixing head and receiving the alternatingly segmented pre-foam stream, with at least one non-reactant materials tank, at least one isocyanate tank, at least one pressurized pre-foam stream feed line and at least one pressurized isocyanate line at a first pressure, and at least one pressurized additive feed line in communication with the mixing head at a second higher pressure. The mixing head may be either stationary or in motion with respect to the conveyor. In addition, a trough or other spreading device may be used to spread the pre-foam stream across the width of the conveyor.
A still further advantageous apparatus of the invention comprises means for providing a pre-foam stream at a first pressure, means for intermittently injecting an additive into the pre-foam stream at a pressure higher than said first pressure, providing a laminar flow pre-foam stream with alternating segments, and means for pouring the pre-foam stream onto a surface, to provide a discretely striped, multi-property foam bun.
The means for intermittently injecting may include at least one injector, the at least one injector preferably injecting the additive into a laminar region of the pre-foam stream while substantially maintaining the laminar flow in the laminar flow region. The apparatus can further comprise a means for controlling the means for intermittently injecting.
The means for controlling the intermittently injecting means may vary the time interval between intermittently injecting and not injecting the additive, wherein the preferred time interval is at least about 0.1 second at most about 10 seconds. The means for controlling the intermittently injecting means can also pulse an injector orifice open and shut or it may control the injector means by varying the size of the orifice of the injector means.
The forming means can comprise a means for pouring said alternatingly segmented pre-foam stream into a form. The form may preferably be a tubular form or a rectangular form. The form may be lined with a separator.
The invention also includes a system for producing a striped foam product, comprising a mixing head for providing a pre-foam stream and at least one injector for injecting an additive into said pre-foam stream to produce a discretely segmented pre-foam stream. The system may preferably include at least one surface for supporting and curing the segmented pre-foam stream into a striped foam bun.
The surface is preferably a conveyor, located at an outlet of the mixing head and receiving the discretely segmented, pre-foam stream. The mixing head is preferably static with respect to the conveyor. The system preferably also includes at least one non-reactant materials tank in communication with the mixing head and providing a pre-foam stream through at least one pressurized pre-foam stream feed line, at least one isocyanate tank in communication with the mixing head and providing an isocyanate stream through at least one pressurized isocyanate line, at least one pressurized additive feed line in communication with the mixing head and providing additive, at least one programmable control unit, and a conveyor for conveying and curing the pre-foam stream mass. Preferably, the control unit controls the three-way valve and intermittently injects the additive at a specified time interval. The control unit may do this by varying the time interval between intermittently injecting and not injecting the additive.
The above objects and advantages of the invention are illustrative and not exhaustive of those which can be achieved by the invention. Thus, these and other objects and advantages of the invention will be apparent from the description herein, both as embodied herein and as modified in view of any variations which would be apparent to those skilled in the art.